Mapping radio-frequency noise in an ultra-wideband communication system

ABSTRACT

A system and method for mapping, radio-frequency (RF) noise, and estimating channel quality in a multi-channel ultra-wideband communication system is provided. One method includes placing a plurality of time bins within a plurality of time frames and assigning a plurality of UWB communication channels comprising selected time bins. RF noise amplitude data is then sampled from selected time bins. The sampled RF noise amplitude data from the time bins is then averaged, thereby obtaining an average RF noise amplitude in each of the plurality of channels. The RF noise amplitude indicates the amount of RF noise present in a channel. The channels may then be ranked based on the characteristics of the RF noise.

This application claims priority under 35 U.S.C. § 120 as a continuationof U.S. patent application Ser. No. 09/802,603, filed Mar. 9, 2001, nowU.S. Pat. No. 6,937,674 entitled “Mapping Radio-Frequency Noise in anUltra-Wideband Communication System”, which claims priority from U.S.provisional application Ser. No. 60/255,469, filed on Dec. 14, 2000,entitled “Ultra-wideband Communication System and Method”, which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The field of the present invention generally relates to wirelesscommunication systems. More particularly, the invention concerns amethod to map radio frequency noise in an ultra-wideband communicationsystem.

BACKGROUND OF THE INVENTION

Wireless communication systems are changing the way people work,entertain themselves, and communicate with each other. For example, thewide acceptance of mobile devices, such as the portable phone, hasenabled great mobility while enabling easy voice and data communicationwith family, friends, and co-workers. As more features are added tothese mobile wireless devices, users are able to receive a wider varietyof information to facilitate enhanced entertainment and to moreefficiently solve business problems. Data, such as computer files,graphics, video, and music may now be sent from a remote location andreceived at mobile wireless devices. Such wide area uses generallyrequire a series of fixed transceivers arranged to communicate with themobile wireless devices. In such a manner, the wireless device isenabled to communicate so long as the wireless device remains in contactwith at least one of the fixed transceivers.

Not only is the use of such wide area systems expanding, but the use oflocal wireless communication systems is also growing. For example,wireless devices in a single building, such as a residence, may beconfigured to share information. Such local wireless communicationsystems may enable computers to control peripherals without physicalconnections, stereo components to communicate, and almost any applianceto have access to the Internet to send and receive information.

The amount of data being sent on both wide and local communicationsystems is mushrooming, and may quickly exceed the bandwidth availablein the traditional communication bands. It has been recognized that arelatively new communication technology, “ultra-wideband” (UWB) mayprovide assistance in meeting the ever increasing bandwidth demands. Forexample, U.S. Pat. No. 6,031,862, entitled “Ultra-wideband CommunicationSystem and Method”, discloses a communication system using an impulseradio system. Impulse radio is a form of UWB communication usingindividually pulsed monocycles emitted at intervals of many nanosecondsto fractions of nanosecond intervals to transmit a digital signal. A UWBcommunication system enables communication at a very high data rate,such as 100 megabit per second or greater.

Currently, with the vast amount of data being sent across local and widearea communication systems, radio frequency (RF) “noise” is impactingthe reliability of data links. Unrelated UWB devices transmitting andreceiving data independent and/or unaware of one another, in conjunctionwith natural or spurious man-made noise can create environments wheresignals “step” on one another (i.e., cancel one another out, amplify orinterfere with one another). For example, UWB devices sending andreceiving data unaware of one another might include instances where twoor more UWB devices or a local home or office network are communicatingin the same environment. Similarly, noise might be generated from alaptop computer, or other devices that can resonate, creating additionalRF noise that can impact UWB communications.

Therefore, there exists a need for an ultra-wideband communicationsystem that can operate reliably in today's noisy RF environment.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies with known, conventionalultra-wideband communication systems, a method for mapping the RF noisefloor is provided. Briefly, the method includes placing a plurality oftime bins within a plurality of time frames and assigning a plurality ofUWB communication channels comprising selected time bins. RF amplitudedata is then sampled from selected time bins. The sampled RF amplitudedata from the time bins is then averaged, thereby obtaining an averageRF amplitude in each of the plurality of channels. The RF amplitudeindicates the amount of RF noise present in a channel.

The channels may then be ranked based on the characteristics of the RFnoise. Channels with low RF noise may be ranked as high qualitychannels, suitable for carrying high data-rate transmissions. Channelswith higher RF noise may then be ranked as lower quality channels,suitable for carrying less data intensive transmissions.

In another aspect of the invention, an absolute value of a differencebetween the RF amplitude average in corresponding time bins in each ofseveral channels is determined, thereby obtaining a change in the RFamplitude average in corresponding time bins across multiple channels.

In another aspect, the present invention further includes steps fordetermining an absolute value of a difference of the change in the RFamplitude average in corresponding time bins across several channels,thereby obtaining a rate of change in the RF amplitude average incorresponding time bins across multiple channels.

The change and rate of change in RF amplitudes (i.e. RF noise) mayindicate whether the RF noise is periodic or substantially constant, orif the RF noise is recurring. One advantage of the present invention isthat UWB channels containing large amounts of RF noise can be avoided,or used to send very low data-rate transmissions, thereby increasing thequality and reliability of UWB communications.

These and other features and advantages of the present invention will beappreciated from review of the following detailed description of theinvention, along with the accompanying figures in which like referencenumerals refer to like elements throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an exemplary ultra-widebandcommunication system capable of utilizing a multiple access scheme inaccordance with an embodiment of the present invention;

FIG. 2 is a flowchart of a process for managing the transmissionsuitability of a multiple access channel in a multi access schemeutilizing a dynamic database controller in a communication system suchas an ultra-wideband communication system in accordance with anembodiment of the present invention;

FIG. 3 a is a schematic diagram of one embodiment of a RF noise sampleremploying a time integrating correlator to correlate the RF noise signalwith a UWB communication channel constructed in accordance with anembodiment of the present invention;

FIG. 3 b is a schematic diagram of a RF noise sampler that utilizesreal-time sampling of time bins in accordance with a preferredembodiment of the present invention;

FIG. 4 illustrates a portion of sampled radio-frequency noise data;

FIG. 5 is a schematic diagram of one method for analyzing RF noise inaccordance with one embodiment of the present invention;

FIG. 6 is a schematic diagram of another process for analyzing RF noisein accordance with another embodiment of the present invention;

FIG. 7 is a schematic diagram of another method for analyzing RF noisein accordance with another embodiment of the present invention;

FIG. 8 is a schematic diagram of another method for analyzing RF noisein accordance with another embodiment of the present invention;

FIG. 9 is a schematic diagram of another embodiment for analyzing RFnoise in accordance with another embodiment of the present invention;

FIG. 10 is a schematic diagram of another embodiment for analyzing RFnoise in accordance with another embodiment of the present invention;

FIG. 11 is a schematic diagram of another method for analyzing RF noisein accordance with another embodiment of the present invention;

FIG. 12 is a schematic diagram of another method for analyzing RF noisein accordance with another embodiment of the present invention; and

FIG. 13 is a schematic diagram of a representative hardware environmentin accordance with an embodiment of the present invention.

It will be recognized that some or all of the figures are schematicrepresentations for purposes of illustration and do not necessarilydepict the actual relative sizes or locations of the elements shown.

DETAILED DESCRIPTION OF THE INVENTION

In the following paragraphs, the present invention will be described indetail by way of example with reference to the attached figures.Throughout this description, the preferred embodiment and examples shownshould be considered as exemplars, rather than as limitations on thepresent invention. As used herein, “the present invention” and “theinvention” refer to any one of the embodiments of the inventiondescribed herein.

“Ultra-wideband” (UWB) is also known as “carrier-free”, “baseband” or“impulse” technology. The basic concept is to develop, transmit andreceive an extremely short duration burst of radio-frequency (RF)energy—typically a few tens of picoseconds (trillionths of a second) toa few hundred nanoseconds (billionths of a second) in duration. Thesebursts represent from one to only a few cycles of an RF carrier wave.The resultant waveforms are extremely broadband, so much so that it isoften difficult to determine an actual RF center frequency—thus, theterm “carrier-free”.

In addition, because of the extremely short duration waveforms of UWBcommunications, packet burst and time division multiple access (TDMA),as well as code division multiple access (CDMA) protocols for multi-usercommunications can be implemented. However, implementation of TDMA andCDMA concepts into a UWB communication system requires novelmethodologies and approaches.

Code Division Multiple Access (CDMA) is a digital spread-spectrummodulation technique that is transmitted over radio frequency waves andused mainly with personal communications devices such as mobile phones.It uses mathematical codes to transmit and distinguish between multiplewireless conversations. CDMA and CDMA-like methods can be used in a UWBcommunication system constructed according to the present invention toincrease the number of users that can be supported from one or more basestations.

Attending the increase of the number of users is an increase of theamount of “noise” generated in the radio frequency (RF) spectrum. Thevast amount of data being sent across communication systems creates avast amount of RF noise, which impacts the reliability of data links.Unrelated UWB devices transmitting and receiving data independent and/orunaware of one another, in conjunction with natural or spurious manmadenoise can create environments where signals “step” on one another (i.e.,cancel one another out, amplify or interfere with one another).

For example, UWB channels sending and receiving data unaware of oneanother might include instances where o or more stand-alone UWB devicesor a local home or office network are communicating in the sameenvironment. Similarly, noise might be generated from a wide variety ofdevices from spark ignition engines to laptop computers. These, or otherdevices can forseeably be generating UWB pulse trains into channelsalready consumed by other UWB activity in the area. This potentiallycauses competition for bandwidth and/or pulse channels that may causedata errors. Inserting a UWB channel into this noise can reduce thequality of the channel, and reception of the UWB channel can be lost, asseparating the noise from the timed pulses can become difficult.

The need to seek out and find a suitable unassigned channels increasesproportionately as a function of increased number of users, increasedchannel capacity demands, and increased noise. In high-density,multi-user, high capacity consumption and/or noisy environments theavailability of acceptable unassigned channels decreases. The resultanteffect can mean greater demands on the system to search for suitableunassigned UWB channels.

To solve this problem, a UWB communication system may employ a pluralityof distinct communication channels that may be managed and organizedusing the methods and devices described in U.S. patent application Ser.No. 09/746,348, entitled “Pretesting and Certification of MultipleAccess Codes”, filed Dec. 21, 2000, and U.S. patent application, serialnumber to be assigned, entitled “Encoding and Decoding Ultra-WidebandInformation,” which are incorporated herein by reference in theirentirety. One aspect of the above-identified invention will provide amethod by which the system will pre-test, rank and assign UWB channelsprior to any actual need for an unassigned channel. This will eliminateinefficiencies in channel allocation function and increase systemefficiency. By constantly testing, analyzing, prioritizing and assigninga list of available channels, reliable and interference-free UWBcommunications will be realized.

The present invention discloses techniques used to digitally map andanalyze the radio frequency (RF) noise floor specifically for UWBcommunications. Allocating channels effectively requires prior knowledgeof the characteristics of the RF environment upon which the UWB channelwill reside. By characterizing the noise that may be present in the timebins that are to be allocated to a channel, a determination can be madeof possible interferences that will make that channel less than optimalfor data transmission.

Referring to FIG. 1, a schematic diagram of an exemplary UWBcommunication system 100 capable of utilizing a multiple access schemein accordance with one embodiment of the present invention isillustrated. One or more wireless mobile units 102 capable of UWBcommunication communicate with a UWB base station 104. The base station104 may communicate directly with the dynamic database controller 106,or it may communicate with the radio-frequency (RF) noise sensingantenna 101. The dynamic database controller 106 communicates with thebase station 104. The dynamic database controller 106 includes a generalcomputing device for executing its functions and communicates with anoise sampler 108 and a dynamic code database 110.

FIG. 2 is a flowchart of a process 200 for managing the transmissionsuitability of a multiple access channel in a multi access schemeutilizing a dynamic database controller 106 in a UWB communicationsystem in accordance with one embodiment of the present invention. Itshould be understood that the term “channel” used in the presentinvention may broadly refer to a multiple access scheme channel wheremultiple access may be achieved by codes, frequency, polarization,phase, etc. In general, information relating to channel noise associatedwith an unallocated channel is obtained utilizing the noise sampler 108in operation 202. The noise sampler 108 may employ a RF noise sensingantenna 101. The dynamic database controller 106 then estimates apotential effect of the channel noise on a transmission quality of anunallocated channel based on the obtained information in operation 204.Next in operation 206, a rating is assigned by dynamic databasecontroller 106 the to the unallocated channel based on the estimatedpotential effect. Based on the assigned rating, the channel isclassified into a grade of service class or classification in operation208. Information relating to the now classified channel and itsassociated rating and grade of service class is then stored in thedatabase 110 in operation 210.

In one embodiment of the present invention, the information relating toRF noise associated with a specific channel may be obtained by samplingthe RF noise and then correlating the RF noise with the channel. FIG. 3a is a schematic diagram of one embodiment of the noise sampler 108illustrated in FIG. 1. In this embodiment, a time integrating correlator306 correlates the RF noise signal with a code sequence. In particular,an RF noise sensing antenna 101 communicates with an RF amplifier 304which communicates with a time integrating generator 306. The timeintegrating generator 306 also communicates with a multiple access codegenerator 308. This embodiment may be suitable for Code DivisionMultiple Access schemes. Time integrating correlators and codegenerators for these codes are known in the art. The RF noise samplesfor this approach may be detected either with the antenna used for datareception or by the dedicated RF noise-sensing antenna 101.

FIG. 3 b is a schematic diagram of a preferred embodiment noise sampler108 that utilizes real-time sampling of time windows or “time bins”.This noise sampler 108 is based on a different access scheme than theaccess scheme utilized in FIG. 3 a. In particular, a RF receivingantenna 310 is coupled to a RF amplifier 312. The RF amplifier 312 and aTime Hopping code generator 314 are both coupled to a multiplexer (MUX)316 which, iii turn is coupled to Hold logic 318. In this noise sampler108, a pseudo-random Time Hopping sequence is used together with a TimeDivision Multiple Access scheme (TH-TDMA). The RF noise sensing antenna101 is used to sense the noise present in the time bins to be occupiedby a particular unallocated Time Hopping sequence. In order to do this,the Time Hopping sequence is used to control the MUX 316 that allows theinput samples to be held and digitized at the appropriate times matchingthe times that would be allocated to the Time Hopping sequence beingtested.

Additional details of the UWB communication system illustrated in FIGS.1-3 b are more fully explained in U.S. patent application Ser. No.09/746,348, entitled “Pretesting and Certification of Multiple AccessCodes”.

FIG. 4 represents a frame of multiple-access data depicting amplitude(A) vs. time (t) and a hypothetical noise signature. In FIG. 4, f_(j)represents the frame number and t_(i) represents a time bin within aframe. The index j runs from 0 to N and the index i runs from 0 to n.Time f₀t₀ is the start of frame zero at time zero and is considered anabsolute time and subsequent times are referenced relative to it. Timef_(j+1)t_(i)−f_(j)t_(i) is the time period for one data frame. Timef_(j)t_(i+1)−f_(j)t_(i) is considered one time bin. The duration of atime bin may vary from approximately 40 picoseconds to approximately 100nanoseconds.

The following section describes a number of different embodiments of thepresent invention that analyze RF noise amplitudes with respect to time.A UWB communication channel constructed according to the presentinvention comprises a plurality of time bins t_(i). All RF amplitudesampling of time bins t_(i) for the following methods can be performedat time,

$\frac{t_{i} + t_{i + 1}}{2}$or in other words, the center of the time bin. Other suitable samplingmethods can also be performed to obtain a sample of RF noise. Obtainingand analyzing RF noise samples may be performed by a programmablegeneral computing device programmed to perform the described operations.This analysis may be performed by the dynamic database controller 106,the dynamic code database 110, or another suitable device.

The following data sample matrix S represents one sample set ofcollected RF noise data, each row is one frame of data and each columnrepresents the same time bin t_(i) in each frame. If N+1 frames aresampled with n time bins in each frame, then the stored matrix is asdepicted in S. A(f_(j)t_(n)) is the amplitude detected in the center ofthe last time bin t_(n) frame f_(j):

$S = \begin{bmatrix}{A\left( {f_{0}t_{0}} \right)} & {A\left( {f_{0}t_{1}} \right)} & \ldots & {A\left( {f_{0}t_{n}} \right)} \\{A\left( {f_{1}t_{0}} \right)} & {A\left( {f_{1}t_{1}} \right)} & \ldots & {A\left( {f_{1}t_{n}} \right)} \\\vdots & \vdots & \; & \; \\{A\left( {f_{N - 1}t_{0}} \right)} & {A\left( {f_{N - 1}t_{1}} \right)} & \ldots & {A\left( {f_{N - 1}t_{n}} \right)} \\{A\left( {f_{N}t_{0}} \right)} & {A\left( {f_{N}t_{1}} \right)} & \ldots & {A\left( {f_{N}t_{n}} \right)}\end{bmatrix}$

The RF noise data samples will probably contain data from otherultra-wideband devices or other types of noise. For example, impulsivenoise such as automobile ignition systems that produce random bursts ofnanosecond pulses or other ultra-wideband time pulses may be present.The following embodiments of the present invention analyze RF noise withrespect to time to determine the amount and nature of noise present inselected channels. Once the noise in each channel is determined, thechannels are ranked based on the amount and type of noise present.

Random noise, also known as additive white Gaussian noise, can beremoved through known techniques and a UWB communication channel can beinserted over additive white Gaussian noise. However, RF noise that issystematically increasing or decreasing cannot be removed and willdecrease the reliability or otherwise interfere with a UWB channelplaced over that noise.

By sampling RF noise data and obtaining the absolute value of thedifferences between selected data, the nature of the noise can bedetermined. The absolute value of the difference of selected RF noisedata samples can show whether or not the noise is increasing ordecreasing. In addition, different embodiments of the inventiondescribed below will also determine the average of the noise, the changein the RF noise from one time bin t_(i) to another time bin t_(i) andthe rate of change of two selected RF noise data samples.

Referring to FIG. 5, a sample average of the same time bins t_(i) overmultiple frames f_(j) of a UWB communication channel constructedaccording to the present invention will be described. The sampleaveraging of the same time bins t_(i) over multiple frames f_(j) isexpressed by the following equation (1):

$\begin{matrix}{\overset{\_}{M\; 1_{i}} = {\frac{1}{N + 1}{\sum\limits_{j = 0}^{N}{A\left( {f_{j}t_{i}} \right)}}}} & (1)\end{matrix}$

This equation takes a column-wise average which produces a vector ofaverages M1 _(i) . Taking column-wise averages produces the a vector ofaverages where A(f_(j)t_(i)) is equal to the sampled amplitude for atime bin, a pulse slot at time i, in frame j. The number of sampleframes is N+1. As shown in FIG. 5, a flowchart illustrates some of thesteps a program will perform to analyze the sampled RF noise data. A UWBcommunication system constructed according to the present invention willemploy one or more programs to perform the analysis now discussed. Theabove equation is performed on matrix S. which contains RF noise datasamples. In step 505, the RF noise amplitude found in the same time bint_(i) in each frame f_(j) is summed. In step 510, that sum of RF noiseamplitudes is averaged. In step 515, the program moves to the nextcolumn representing a second time bin t_(i+1). The sum for the secondcolumn is then averaged in step 510, and this process of summing eachcolumn representing a distinct time bin t_(i) is repeated until all ofthe time bins t_(i) in all of the frames f_(j) have been summed andaveraged, finishing at step 520.

The resultant average for each time bin t_(i) represents the average RFnoise amplitude for that specific time period. After step 520, the RFnoise amplitudes for adjacent time periods can then be evaluated todetect if a periodic signal with a main periodicity of one frame f_(j)is present. If periodic noise is present, an estimation of the effect ofthe noise on the transmission quality is performed by the dynamicdatabase controller 106, illustrated in FIG. 2.

Referring to FIG. 6, another process according to the present inventionis illustrated which evaluates the RF noise amplitude data. The processillustrated in FIG. 6 takes a first difference of adjacent time binst_(i) within a frame f_(j). This is expressed by the following equation(2):M2_(ij) =|A(f _(j) t _(i+1))−A(f _(j) t _(i))|.  (2)

In step 605, the difference of the amplitudes of RF noise samples inadjacent time bins t_(i) in the same frame f_(j) is taken. This processis repeated in step 605 until all of the adjacent time bins t_(i) in oneframe f_(j) have been evaluated. In step 610, when the end of the frameis reached, the next frame f_(j+1) is analyzed according to step 605. Inthis manner, all of the adjacent time bins t_(i) in a plurality offrames f_(j) are evaluated. This first difference calculation M2 _(if)obtains the difference in RF noise amplitudes in adjacent time binst_(i) within a frame f_(j). At step 615, when all of the RF noisesamples have been analyzed, this information can be used to determine ifthe RF noise is increasing or decreasing with time by the dynamicdatabase controller 106.

Alternatively, the data obtained by equation (1) can be used to obtainthe absolute value of a difference of adjacent time bin t_(i) RF noiseamplitude averages. This process is expressed by the following equation(3):M2_(i) =| M1_(i+1) − M1_(i) |.  (3)

In equation (3), an absolute value of the difference between averaged RFnoise samples in adjacent time bins t_(i) is obtained. The data obtainedafter this analysis will be used by the dynamic database controller 106,or other suitable device to determine the change in RF noise amplitudesin adjacent time bins t_(i).

Referring to FIG. 7, a process to obtain a second difference of adjacenttime bins t_(i) is illustrated. This process uses the data obtained fromequation (2). The process illustrated in FIG. 7 takes a seconddifference of adjacent time bins 6 within a frame f_(j). This isexpressed by the following equation (4):M3_(ij) =|M2_(i+1) −M2_(i)|  (4)

In step 705, the absolute value of the difference of the change inadjacent time bins 6 in the same frame f_(j) is obtained. This processis repeated in step 705 until all of the adjacent time bins 6 in oneframe f_(j) have been evaluated. In step 710, when the end of the frameis reached, the next frame f_(j) is analyzed according to step 705. Inthis manner, all of the adjacent time bins 6 and a plurality of framesf_(j) are evaluated. This second difference calculation M3˜obtains thesecond difference of RF noise amplitudes of adjacent time bins 6 withina frame f_(j). At step 715, when all of the RF noise samples have beenanalyzed, this information can be used to determine the rate of changeof the RF noise by the dynamic database controller 106, or othersuitable devices. The rate of change of the RF noise can help todetermine the quality of a channel and can also be used to estimate apotential effect of the noise on a transmission.

Alternatively, the data obtained by equation (3) can be used to obtainthe absolute value of a second difference of adjacent time bin t_(i) RFnoise amplitude averages. This process is expressed in the followingequation (5):M3_(i) =| M2_(i+1) − M2_(i) .  (5)

In equation (5), an absolute value of the second difference betweenaveraged RF noise samples in adjacent time bins t_(i) is obtained. Thisdata is used by the dynamic database controller 106, or other suitabledevice to determine the rate of change, or how fast the RF noiseamplitudes in adjacent time bins t_(i) is changing.

Referring to FIG. 8, an alternative process for evaluating the RF noiseamplitude in a data sample for use in an UWB communication systemconstructed according to the present invention is illustrated. Referringto FIG. 8, a first difference of the same time bins t_(i) over multipleframes f_(j) is obtained. This is expressed by the following equation(6):M4_(ji) =|A(f _(j+1) t _(i))−A(f _(j) t _(i))|.  (6)

This process uses sampled RF amplitude data from two consecutive framesf_(j) contained in the matrix S. defined above. This is illustrated instep 805 of FIG. 8 where the absolute value of the difference betweenthe same time bin t_(i) in adjacent frames f_(j) is calculated. In step810, the difference of adjacent time bins t_(i) is repeated until all ofthe frames f_(j) have been evaluated. When the last frame f_(j) has beenevaluated, the program continues by moving to the next time bin t, instep 815. In this manner, all time bins t_(i) in a sample of RF noiseamplitude data is evaluated.

This process obtains a change in the RF noise amplitude in correspondingtime bins 6 across successive frames f_(j). At step 820, the process iscomplete, and the dynamic database controller 106 conducts an analysisof whether or not a detected RF noise may be repetitive. If a repetitiveRF noise is found through this analysis, it can be avoided therebyimproving the quality and reliability of UWB communications performedaccording to the present invention.

Referring to FIG. 9, a process to obtain a second difference of the sametime bin 6 over multiple frames f_(j) is illustrated. This process isexpressed by the following equation (7):M5_(ji) =M4_(i+1) −M4_(i)|  (7)

In the above equation, the rate of change of the RF noise amplitude incorresponding time bins t_(i) across successive frames f_(j) isdetermined. In step 905, the absolute value of the difference of thechange in the same time bins 6 across multiple frames f_(j) is obtained.In step 910, when the end of a column of frames f_(j) is reached, theprogram increments to the next time bin t_(i) in step 915. This processis repeated until all of the differences of the same time bins t_(i) areobtained for all frames f_(j). In step 920, the process is complete, andthe dynamic database controller 106 uses this information to determinethe rate of change of the RF noise amplitude data in corresponding timebins 6. The rate of change information can help to determine thecharacteristic of the RF noise amplitudes in specific time bins t_(i).

Referring to FIGS. 10-12, a preferred embodiment of the presentinvention is illustrated. Shown in FIGS. 10-12 are processes used toexamine RF noise amplitude in pseudo-randomly spaced time bins. Asdiscussed in prior sections, pseudo-random distribution of time bins isaccomplished through “time-hopping”. In a preferred embodiment of theinvention, a plurality of pseudo-randomly spaced time bins are selectedand allocated to a specific channel. in this manner, a plurality ofchannels each comprising a plurality of time bins that do not overlapcan be transmitted simultaneously. The number of time bins in eachchannel is determined according to the bandwidth requirement for thetype of information communicated in that channel. As discussed above,the plurality of pseudo-randomly spaced time bins are located within aframe f. The number of channels possible in a frame is determinedaccording to the following equation: possible channels=(int) N/b. Thatis, the number of possible channels equals the integer portion of thequotient of the number of time bins available per frame divided by thedesired time bins per channel per frame.

Referring to FIG. 10, a process to obtain sample average of a singlechannel comprising a plurality of time bins tk located in multipleframes f_(j) is illustrated. The sample averaging of the plurality offrames f_(j) and time bins 6 is expressed by the following equation (8):

$\begin{matrix}{\overset{\_}{M\; 6_{j}} = {\frac{1}{N + 1}{\sum\limits_{j = 0}^{N}{\sum\limits_{k = 1}^{b}{A\left( {f_{f}t_{k}} \right)}}}}} & (8)\end{matrix}$

In the above equation, f_(j) is equal to frame j, tk is the k^(th) timebin allocated to the same channel and frame f_(j), k is a frame-periodicpseudo-noise sequence of length b and N is the number of frames overwhich the sequence is averaged. Illustrated in FIG. 10 is a flowchartillustrating the steps a program will perform to analyze sampled RFnoise data.

The following data sample matrix T is used by equation (8). Matrix Trepresents one sample set of collected RF noise data, wherein each rowis one frame of data and each column represents a pseudo-randomly placedtime bin t. If N+1 frames are sampled with b time bins in each frame,then the stored matrix is as depicted in T. A(f_(j)t_(b)) is theamplitude detected in the center of the time bins t_(b) in frame f_(j):

$T = \begin{bmatrix}{A\left( {f_{0}\; t_{0}} \right)} & {A\left( {f_{0}\; t_{1}} \right)} & \ldots & {A\left( {f_{0}\; t_{b}} \right)} \\{A\left( {f_{1}\; t_{0}} \right)} & {A\left( {f_{1}\; t_{1}} \right)} & \ldots & {A\left( {f_{1}\; t_{b}} \right)} \\\vdots & \vdots & \; & \; \\{A\left( {f_{N - 1}\; t_{0}} \right)} & {A\left( {f_{N - 1}\; t_{1}} \right)} & \ldots & {A\left( {f_{N - 1}\; t_{b}} \right)} \\{A\left( {f_{N}\; t_{0}} \right)} & {A\left( {f_{N}\; t_{1}} \right)} & \ldots & {A\left( {f_{N}\; t_{b}} \right)}\end{bmatrix}$

In step 1010, the RF noise amplitude found in the same pseudo-randomlyplaced time bin t_(b) in each frame f_(j) is summed. In step 1010, thatsum of RF noise amplitudes is averaged. In step 1015, the program movesto the next column representing a second pseudo-randomly placed time bint_(b). The sum for the second column is then averaged in step 1010, andthis process of summing each column representing a pseudo-randomlyplaced time bin t_(b) is repeated until all of the pseudo-randomlyplaced time bins t_(b) in all of the frames f_(j) have been summed andaveraged, finishing at step 1020. The resultant average for eachpseudo-randomly placed time bin t_(b) represents the average RF noiseamplitude for that specific channel to which the pseudo-randomly placedtime bins t_(b) have been allocated. After step 1020, the RF noiseamplitudes for the specific channel can then be evaluated to detect if aperiodic signal or other types of RF noise is present. If RF noise ispresent, an estimation of the effect of the noise on the transmissionquality is performed by the dynamic database controller 106, illustratedin FIG. 2. Additionally, the data obtained from the process illustratedin FIG. 10 can be used to rank channel quality based on the RF noisepresent in that UWB communication channel.

Referring to FIG. 11, another process according to the present inventionis illustrated which evaluates the RF noise amplitude data. The processillustrated in FIG. 11 takes a first difference of pseudo-randomlyplaced time bins t_(b) within a frame f_(j). This is expressed by thefollowing equation (9):M7_(j) =|A(f _(j) t _(i))−A(f _(j) t _(k))|,  (9)where t_(i) is the pseudo-randomly placed time bin that follows t_(i),in the pseudo-randomly placed sequence allocated to a specific UWBcommunication channel. That is, t_(l) is not the temporally next timebin but instead is the time bin that next follows t_(k) in a sequence ofpseudo-randomly placed time bins. In step 1105, the difference of theamplitudes of RF noise samples in pseudo-randomly placed time bins t_(b)in the same frame f_(j) is taken. This process is repeated until all ofthe pseudo-randomly placed time bins b allocated to a specific channelin one frame f_(j) have been evaluated. In step 1110, when the end ofthe frame f_(j) is reached, the next frame f_(j) is analyzed accordingto step 1105. In this manner, all of the pseudo-randomly placed timebins t_(b) in a plurality of frames f_(j) are evaluated. This firstdifference calculation M7 _(j) obtains the difference in RF noiseamplitudes in sequential pseudo-randomly placed time bins within aframe. At step 1115, when all of the RF noise samples have beenanalyzed, this information may be used to determine if the RF noise isincreasing or decreasing in the specific UWB communication channel thathas been allocated to those sampled pseudo-randomly placed time binst_(b). Alternatively, the data obtained by equation (8) can be used toobtain the absolute value of a difference of the RF noise amplitudeaverages in channel adjacent pseudo-randomly placed time bins t_(b).This process is expressed by the following equation (10):M7_(j) =| M6_(l) − M6_(k) |  (10)

In equation (10), an absolute value of the difference between averagedRF noise samples in channel adjacent pseudo-randomly placed time binst_(b) is obtained. M6 _(l) is the time bin that follows M6 _(k) in asequence of pseudo-randomly placed time bins allocated to a specific UWBcommunication channel. These time bins are referred to as “channeladjacent” time bins. The data obtained after this analysis will be usedby the dynamic database controller 106, or other suitable device todetermine the change in RF noise amplitudes in a UWB communicationchannel that has been allocated specific pseudo-randomly placed timebins.

Referring to FIG. 12, a process to obtain a second difference ofpseudo-random time bins t_(b) is illustrated. This process uses the dataobtained from equation (10). The process illustrated in FIG. 12 takes asecond difference of channel adjacent pseudo-randomly placed time binst_(b) within a frame f_(j). This is expressed by the following equation(11):M8_(j) −M7_(l) −M7_(k)|  (11)

Again, M7 _(l) is the time bin that follows M7 _(k) in a sequence ofpseudo-randomly placed time bins allocated to a specific UWBcommunication channel.

In step 1205, the absolute value of the difference of the change inchannel adjacent pseudo-randomly placed time bins t_(b) in the sameframe f_(j) is obtained. This process is repeated in step 1205 until allof the data from equation (10) has been evaluated. In step 1210, whenthe end of the frame f_(j) is reached, the next frame f_(j) is analyzedaccording to step 1205. In this manner, all of the data from equation(10) is evaluated. This second difference calculation MS1 obtains thesecond difference of RF noise amplitudes of channel adjacent time binst_(b) within a frame f_(j). At step 1215, when all of the RF noisesamples have been analyzed, this information may be used to determinethe quality of a channel which will later be used in the process forranking channels to be described below.

Alternatively, the data obtained by equation (10) can be used to obtainthe absolute value of a second difference of channel adjacent time bint_(b) RF noise amplitude averages. This process is expressed in thefollowing equation (12):M8_(j) =| M7_(l) − M7_(k) |  (12)

In equation (12) an absolute value of the second difference betweenaveraged RF noise samples in channel adjacent time bins t_(b) isobtained. This data is used by the dynamic database controller 106, orother suitable device to determine the rate of change, or how fast theRF noise amplitudes in adjacent pseudo-random time bins t_(b) ischanging.

The above-described methods and processes are used to obtain andmanipulate data used for evaluating RF noise amplitudes that may bepresent during transmission of a UWB communication channel constructedaccording to the present invention. The above-described methods quantifythe type of RF noise that may be present. For example, narrow durationnoise, wide duration noise, additive white Gaussian noise, repetitivenoise, and other types of RF noise can all be evaluated using theabove-described methods. This information is used to grade or rank eachUWB channel that is to be transmitted. In one embodiment of the presentinvention, time bins will be created to correspond with each UWBchannel's statistical probability for optimum suitability in descendingorder from channels of highest quality to channels of lowest quality.For example, a channel assigned for the transmission of data whichrequires high transmission rates would receive a high quality channelcontaining low or non-existent amounts of RF noise. A UWB channelassigned to carry video data may receive a slightly lower qualitychannel that has slightly higher amounts of RF noise present. A UWBchannel for transmitting audio signals may receive a low quality channelcontaining high amounts of RF noise, and some UWB channels may not beallocated any data because analysis has indicated that the RF noisepresent is too great to carry any data reliably.

The information derived from the above-described methods may be used tograde and assign each channel into time bins identified for optimumchannel bandwidth. Time bins will ideally be created to correspond toeach channel's statistical probability for optimum suitability indescending order from Data (channels of highest quality), Video (nexthighest quality), Audio (lowest quality) and “Not Suitable” (channelquality is not suitable for pulse train insertion).

The reliability of a UWB communication channel constructed according tothe present invention can be evaluated by determining the projected biterror rate (PBER). One process for evaluating a PBER in a IJ\VB channelconstructed according to the present invention is expressed in thefollowing equation (13):

$\begin{matrix}{{PBER} = {{- \frac{\ln\left( {1 - {CL}} \right)}{n}} + \frac{\ln\left( {\sum\limits_{k = 0}^{N}\frac{\left( {n \cdot {PBER}} \right)^{k}}{k!}} \right)}{n}}} & (13)\end{matrix}$

where n is the number of bits transmitted in an ultra-widebandcommunication channel, and CL is the confidence level (that is, thestatistical confidence that the bit error rate (BER) will be less thanor equal to the PBER). N is the total number of bit errors that occurduring the transmission, and k refers to the k^(th) bit error. Thisequation can be solved by iterative methods by inserting CL, and yieldsa PBER that is constantly updated as a transmission proceeds. Forexample, a CL of 0.95 can be inserted into the equation and a PBER canbe determined. As the FBER changes, the amount of data transmitted maybe decreased to maintain channel quality or the data transmission onthat specific channel may be terminated and switched to anotherultra-wideband channel with a lower PBER.

FIG. 13 illustrates a representative hardware environment or workstationby which embodiments of the present invention may be carried out. In thepresent invention, the various sub-components of each of the componentsembodying the invention may also be considered components of the UWBcommunication system. For example, particular software modules executedon any component of the system may also be considered components of thesystem. The hardware configuration illustrated in FIG. 13 includes acentral processing unit 20. such as a microprocessor, and a number ofother units interconnected via a system bus 25.

The workstation shown in FIG. 13 includes a Random Access Memory (RAM)30, Read Only Memory (ROM) 35, an I/O adapter 40 for connectingperipheral devices such as disk storage units 42 to the bus 25, a userinterface adapter 45 for connecting a keyboard 50, a mouse 55, a speaker60, a microphone 65, and/or other user interface devices such as a touchscreen (not shown) to the bus 25, communication adapter 70 forconnecting the workstation to a communication network 75 (e.g., a dataprocessing network) and a display adapter 80 for connecting the bus 25to a display device 85.

An embodiment of the present invention may he written using JAVA, C,C++, or other suitable computer languages and may utilize objectoriented programming methodology.

Thus, it is seen that an apparatus and method for mapping RF noise in aUWB communication system is provided. One skilled in the art willappreciate that the present invention can be practiced by other than thepreferred embodiments, which are presented in this description forpurposes of illustration and not of limitation, and the presentinvention is limited only by the claims that follow. It is noted thatvarious equivalents for the particular embodiments discussed in thisdescription may practice the invention as well.

1. A method for estimating channel quality in a multi-channel ultra-wideband communication system, the method comprising the steps of: pseudo-randomly placing a plurality of time bins within a plurality of time frames, each time bin comprising one or more data bits; assigning a plurality of channels comprising selected pseudo-randomly placed time bins; transmitting a multiplicity of data bits through the plurality of channels; monitoring the number of data bits transmitted through each channel; determining a number of data bit errors in the transmissions; determining a projected bit error rate for at least one transmission; and grading a channel quality using at least the projected bit error rate.
 2. The method for estimating channel quality in a multi-channel ultra-wideband communication system of claim 1, wherein determining a projected bit error rate for at least one transmission is obtained iteratively through the following equation: ${PBER} = {{- \frac{\ln\left( {1 - {CL}} \right)}{n}} + \frac{\ln\left( {\sum\limits_{k = 0}^{N}\frac{\left( {n \cdot {PBER}} \right)^{k}}{k!}} \right)}{n}}$ where PBER is a projected value of the bit error rate, n is the number of bits transmitted, CL is a confidence level, N is the total number of bit errors that occur during the transmission, and k refers to a k^(th) bit error.
 3. The method for estimating channel quality in a multi-channel ultra-wideband communication system of claim 2, wherein the confidence level CL is a statistical confidence that the bit error rate will be less than or equal to the projected bit error rate.
 4. A method for estimating channel quality in a multi-channel ultra-wideband communication system, comprising: means for pseudo-randomly placing a plurality of time bins within a plurality of time frames, each time bin comprising one or more data bits; means for assigning a plurality of channels comprising selected pseudo-randomly placed time bins; means for transmitting a multiplicity of data bits through the plurality of channels; monitoring the number of data bits transmitted through each channel; determining a number of data bit errors in the transmissions; means for determining a projected bit error rate for at least one transmission; and grading a channel quality using at least the projected bit error rate.
 5. The method for estimating channel quality in a multi-channel ultra-wideband communication system of claim 4, wherein determining a projected bit error rate for at least one transmission is obtained iteratively through the following equation: ${PBER} = {{- \frac{\ln\left( {1 - {CL}} \right)}{n}} + \frac{\ln\left( {\sum\limits_{k = 0}^{N}\frac{\left( {n \cdot {PBER}} \right)^{k}}{k!}} \right)}{n}}$ where PBER is a projected value of the bit error rate, n is the number of bits transmitted, CL is a confidence level, N is the total number of bit errors that occur during the transmission, and k refers to a k^(th) bit error.
 6. The method for estimating channel quality in a multi-channel ultra-wideband communication system of claim 5, wherein the confidence level CL is a statistical confidence that the bit error rate will be less than or equal to the projected bit error rate. 